Population Dynamics and Exploitation Level of Stolothrissa tanganicae Regan, 1917 and Limnothrissa miodon (Boulenger, 1906), Two Clupeid Fish Species of Commercial Interest of Burundian Waters Northeast of Lake Tanganyika

Abstract

Aims: Show exploitation level and propose rational management measures of the two clupeid-fish species of commercial interest, Stolothrissa tanganicae and Limnothrissa miodon Study Design:  Modeling the demography of clupeid fishes of Lake Tanganyika. Place and Duration of Study: Two stations (Kajaga and Nyamugari) situated in the northern part of Lake Tanganyika on the Burundian coast from December 2019 to April 2020. Methodology: Monthly fish sampling was done with local fishermen Demographic parameters were determined according to the Von Bertalanffy growth model using size frequency distributions based on total length. Excel 2013 and FAO-ICLARM. Stock Assessment Tools (FiSAT II version 1.2.2 software). Results: The values of the growth parameters obtained for each of the two species are close at the level of the two stations. For S. tanganicae, we have L∞= 135 mm and 118 m and K=0.94 yr-1 and 0.99 yr-1 respectively at Kajaga and Nyamugari. For L. miodon, we have L∞= 148 mm and 132 m and K=1.04 yr-1 and 0.92 yr-1 respectively at Kajaga and Nyamugari. The Ø' values obtained are high and vary from 4.14 to 4.58 depending on the species and the stations: For S. tanganicae, higher Ø' was recorded at Kajaga (Ø'= 4.23). In L. miodon, it was observed at Nyamugari (Ø’=4.58). M oscillate around 1 (M varies from 1.08 to 1.17 year-1) for the two species at two stations. F is high everywhere and varies from 3.03 to 6.49 yr-1 depending on the species and the stations. Both species are overexploited : 0.73<E<0.86, so E is close to 1. Small-sized individuals dominate catches: minimum sizes are between 24 and 30  and 42 and 54 mm  respectively in L. miodon and in S. tanganicae. Both the fish species adapt well to their environments (the values of Ø' are very high). Conclusion: Both species of fish adapt well to their environments (the values of Ø' are very high). Given their overexploitation, the existing rational management measures must be strengthened and rigorously applied.